Answer: The fungus involved with Armillaria Root Rot can contaminate tree roots if new trees are planted in soil that originally held infected roots and those roots were left behind to decay. Planting in raised beds with fresh soil should protect your Lorapetalum. Remove one of the dead trees and inspect the roots, looking for shoestring-looking mats of fungus. If you find them, suspect Armillaria. If you don't find a fungal infection, I'd suspect poorly draining soil (unusual in raised beds), or lack of water during the growing season. Best wishes with your remaining trees!
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